Moving a pair of mandrel cradles

ABSTRACT

A device for assembling a composite structure is disclosed. An illustrative embodiment of the device includes at least one carriage track, a linear rail carriage carried by the at least one carriage track, a yoke assembly carried by the linear rail carriage, a linear actuator assembly engaging the linear rail carriage and adapted to move the linear rail carriage along the at least one carriage track and a pair of mandrel cradles pivotally carried by the yoke assembly. Activation of the linear actuator assembly facilitates movement of the linear rail carriage along the at least one carriage track and pivoting of the pair of mandrel cradles with respect to the yoke assembly.

FIELD

The present invention relates to apparatuses and methods for assemblingcomposite structures such as aircraft stringers. More particularly, thepresent invention relates to a composite structure assembly table andmethod for the automated assembly of composite structures such asaircraft wing stringers.

BACKGROUND

Composite structures are used extensively in aircraft and otherapplications in which materials having a high strength-to-weight ratioare necessary. However, composite structures are costly sincefabrication of such structures requires the layering of multiplematerials. Depending on the particular application, a compositestructure may be formed by layering individual sheets of material eithermanually or using an automated apparatus.

One type of composite structure which is commonly used as a supportelement in aircraft is the “I” beam or “T” stringer. These beam-typecomposite structures are generally formed by manually placing layers ofcomposite material over a lay-up mandrel. An automated cutting machinecuts each layer of material, or prepreg, to the proper shape. Theindividual layers of the prepreg are then manually placed on separatelay-up mandrels. Once positioned, each layer of prepreg is manuallyconformed to the exterior contour of each lay-up mandrel to form twoC-channels. Next, the C-channels and lay-up mandrels are rotated tofacilitate joining of the C-channels to each other along their webs toform an I-beam. A radius filler is then placed in the triangularrecesses formed in the center of the top and bottom flanges of theI-beam. Top and bottom composite reinforcement layers are then manuallyplaced over the radius filler, which is then bagged and autoclave-cured.

The manual I-beam or stringer fabrication process is labor-intensive,time-consuming and attended by quality control issues. Therefore,automated methods of fabricating composite structures are beingdeveloped due to the drawbacks which are associated with manualfabrication of composite structures.

SUMMARY

The present invention is generally directed to a device for assembling acomposite structure. An illustrative embodiment of the device includesat least one carriage track, a linear rail carriage carried by the atleast one carriage track, a yoke assembly carried by the linear railcarriage, a linear actuator assembly engaging the linear rail carriageand adapted to move the linear rail carriage along the at least onecarriage track and a pair of mandrel cradles pivotally carried by theyoke assembly. Activation of the linear actuator assembly facilitatesmovement of the linear rail carriage along the at least one carriagetrack and pivoting of the pair of mandrel cradles with respect to theyoke assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, by way of example, with reference tothe accompanying drawings, in which:

FIG. 1 is a perspective view of a table module of an illustrativeembodiment of the structure assembly table, which table module includesmultiple adjacent module units.

FIG. 2 is an end view of a module unit of the structure assembly table,more particularly illustrating a riser block, a flipper assembly, aflopper assembly and a compactor head which in concert with each otherimplement automated fabrication of a composite structure.

FIG. 3 is a perspective view of multiple flipper assemblies inrespective module units (not shown) of the structure assembly table,with a composite structure being positioned by the flipper assemblies.

FIG. 4 is a perspective view of an adjustable position flipper elementof each flipper assembly.

FIG. 5 is a perspective view of multiple flopper assemblies inrespective module units (not shown) of the structure assembly table,with separate components of a composite structure being positioned bythe respective flopper assemblies.

FIG. 6 is a perspective view of a flopper assembly of a correspondingmodule unit of the structure assembly table.

FIG. 7 is a top view of a positioning assembly of the structure assemblytable.

FIG. 8 is a front view of a positioning assembly of the structureassembly table.

FIGS. 9-38 illustrate sequential fabrication of a composite structure intypical implementation of the structure assembly table.

DETAILED DESCRIPTION

Referring to FIGS. 1-8, an illustrative embodiment of the structureassembly table is generally indicated by reference numeral 1. As shownin FIG. 1, the structure assembly table 1 includes a table module 2having a generally elongated, box-shaped table module frame 3. The tablemodule 2 includes multiple, adjacent module units 8, each of which is afunctional subunit of the structure assembly table 1. In theillustrative embodiment of the invention shown in FIG. 1, the structureassembly table 1 includes six module units 8; however, it is to beunderstood that the structure assembly table 1 may have a smaller orlarger number of module units 8 depending on the application of thestructure assembly table 1. As shown in FIG. 2, for purposes ofdescription herein, the structure assembly table 1 has an operator side4 and a non-operator side 5.

As will be hereinafter described, the structure assembly table 1 issuitable for implementing the assembly of a composite structure 87 (FIG.3) such as an aircraft wing stringer, for example. The structureassembly table 1 is highly reconfigurable via computer softwaremodifications. The modularity of the structure assembly table 1accommodates multiple composite structure configurations. The modularcomponents of the structure assembly table 1 are designed to beinterchangeable and serviceable through typical remove-and-replacemethods. Multiple structure assembly tables 1 can be placed inend-to-end relationship with respect to each other to facilitatefabrication of composite structures having various sizes andconfigurations.

As will be hereinafter further described, the structure assembly table 1includes a bank of six devices or assemblies which are operable toindex, lift, rotate and set individual and opposite composite structuresubassemblies such as stringer mandrels, for example. Another bank offive computer-controlled shuttling or positioning devices or assemblieslifts and positions the two composite structure subassemblies relativeto each other and ensures proper spacing and parallelism of thesubassemblies through a series of sensing routines. A bank of sixcomputer-controlled pneumatic compactor devices compacts the individualsubassemblies together, after which a bank of flipper assemblies rotatesthe composite structure to the operator side 4 of the structure assemblytable 1. The flipper assemblies capture the subassemblies and positionthe subassemblies with respect to each other while accommodating fortaper and ply thickness changes along the length of each to securelyrotate the composite structure. In cases in which the compositestructure is an aircraft stringer, after radius filler and cap aremanually applied to one exposed side of the mandrel assembly, theflipper assembly then rotates the mandrel assembly back to thenon-operator side 5 of the structure assembly table 1 where the mandrelassembly is then lifted and shuttled back to the operator side 4 forapplication of radius filler and cap on the opposite side of theassembly.

As shown in FIGS. 1 and 2, each module unit 8 includes a generallyelongated, rectangular module unit frame 9 which is supported by thetable module frame 3. A frame divider 10 may extend through the centerportion of the module unit frame 9. As shown in FIG. 1, unit connectors11 connect the module unit frames 9 of the adjacent module units 8 toeach other. A top plate 14 is provided on the table module frame 3,between adjacent module units 8. A module slot 16 extends betweenadjacent top plates 14.

As shown in FIGS. 2 and 3, each module unit 8 of the table module 2includes a flipper assembly 18. As shown in FIG. 3, the flipperassemblies 18 of the respective module units 8 form a bank of flipperassemblies 18 which carry out the rotating functions of the structureassembly table 1, as will be hereinafter described. Each flipperassembly 18 is disposed beneath the module slot 16 of each correspondingmodule unit 8. Each flipper assembly 18 includes a fixed positionflipper device 19 typically having an electro/mechanically actuatedlinear positioning screw 20 which is pivotally attached to the moduleunit frame 9 via a pivot pin 25. A ballscrew 21 is extendable from theballscrew housing 20. A flipper blade frame 22 is pivotally attached tothe ballscrew 21 via a pivot pin 24. A generally elongated, rectangularflipper blade 23 is provided on the flipper blade frame 22. Accordingly,by selective actuation of the actuating ballscrew housing 20 andactuating ballscrew 21, the flipper blade 23 of the fixed positionflipper device 19 can be positioned between a generally horizontalposition (not shown) and the generally vertical position shown in FIG.27, in which vertical position the flipper blade 23 extends through themodule slot 16 of the corresponding module unit 8. A support pin 26extends from the proximal end portion of the flipper blade 23, ingenerally perpendicular relationship with respect to the longitudinalaxis of the flipper blade 23.

As shown in FIG. 3, each flipper assembly 18 further includes anadjustable position flipper device 30 which is opposite the fixedposition flipper device 19. As shown in FIG. 4, the adjustable positionflipper device 30 includes a containment frame 31. The containment frame31 is provided on a linear slide 38, which is typically ballscrewactuated, to facilitate selective movement of the containment frame 31toward and away from the corresponding paired or opposite fixed positionflipper device 19. A ballscrew housing 36 is provided in the containmentframe 31. A ballscrew 37 is selectively extendable from the ballscrewhousing 36.

A pair of spaced-apart frame flanges 32 extends from the containmentframe 31. A pivot rod 33 extends between the frame flanges 32. Anelongated flipper blade frame 34 is pivotally mounted on the pivot rod33. As further shown in FIG. 4, on one side of the pivot rod 33, theballscrew 37 pivotally engages a first end of the flipper blade frame 34via a pivot pin 33 a. A generally elongated, rectangular flipper blade35 extends from a second end of the flipper blade frame 34 on theopposite side of the pivot rod 33. Accordingly, by selective actuationof the ballscrew housing 36 and ballscrew 37, the flipper blade 35 ofthe adjustable position flipper device 30 can be positioned between agenerally horizontal position (not shown) and the generally verticalposition shown in FIG. 27, in which vertical position the flipper blade35 extends through the module slot 16 of the corresponding module unit8. A support pin 39 extends from the proximal end portion of the flipperblade 35, in generally perpendicular relationship with respect to thelongitudinal axis of the flipper blade 35. A controller (not shown) isconnected to the ballscrew housing 20 of each fixed position flipperdevice 19 and the ballscrew housing 36 of each adjustable positionflipper device 30 to facilitate operation of the flipper assemblies 18of the module units 8 in concert with each other.

As shown in FIGS. 2, 5 and 6, each module unit 8 of the table module 2further includes a flopper assembly 44 which is adjacent to thecorresponding flipper assembly 18. The flopper assemblies 44 are adaptedto index, lift, rotate and set opposing composite structure subunits ina simple linear actuation preparatory to fabrication of the compositestructure. As shown in FIG. 2, the flipper assembly 18 and the flopperassembly 44 are typically located on opposite sides of the frame divider10. The flopper assemblies 44 of the respective module units 8 form abank of flopper assemblies 44 which carry out relative placement orpositioning of the composite structure component subunits with respectto each other in operation of the structure assembly table 1, as shownin FIG. 5 and will be hereinafter described. As shown in FIG. 6, eachflopper assembly 44 includes a three-walled cabinet 55 having a trackplate 59 which is attached to the module unit frame 9 of each moduleunit 8 according to the knowledge of those skilled in the art. A pair ofspaced-apart side plates 54 extends from respective ends of the trackplate 59. At least one carriage track 58 is provided on the track plate59. As shown in FIG. 6, a pair of generally parallel, spaced-apartcarriage tracks 58 may be provided on the track plate 59. A linear railcarriage 57 slidably engages the carriage tracks 58. A yoke assembly 56is provided on the linear rail carriage 57. As shown in FIG. 2, a pairof jack screw housing servo motors (I/O) includes a pair of jack screwhousings 63 provided on the module unit frame 9. A pair of jack screwsand ball nuts 63 a is extendable from the stabilizing jack screwhousings 63, respectively. The stabilizing jack screws and ball nuts 63a engage the linear rail carriage 57 through a gang connection 62 andactuate movement of the linear rail carriages 57 of the flopperassemblies 44 in concert along the respective pairs of carriage tracks58.

As shown in FIG. 6, a flopper frame 45 includes an elongated crosspiece46 which is provided on the yoke assembly 56. A slotted cradle support47 extends from each end of the crosspiece 46. Cradle position blocks 49and 51 are pivotally attached to each cradle support 47. Accordingly, acurved track groove 50 provides tracking on cradle position block 49. Aball plunger 53 extends through a plunger opening (not shown) providedin the cradle support 47 and through to the track groove 50. Anelongated slider link 48 is attached to each side plate 54 of thecabinet 55. Each cradle position block 49 is pivotally attached to thecorresponding slider link 48 typically via a pivot pin (not shown)located above a ball detent 52 which extends through the slider link 48and position block 49.

An L-shaped mandrel cradle 51 is provided on each cradle position block49. Accordingly, each mandrel cradle 51 is selectively positionalbetween a first position shown in FIG. 11 and a second position shown inFIG. 13, in which second position the mandrel cradle 51 has been rotated90 degrees with respect to the first position, according to a techniquewhich will be hereinafter described. Depending on the position of thelinear rail carriage 57 and yoke assembly 56 on the carriage tracks 58of the cabinet 55, each pair of mandrel cradles 51 extends through themodule slot 16 of the corresponding module unit 8, as shown in FIGS. 13and 14, or is disposed beneath the top surface of the module unit 8, asshown in FIG. 15. At least one pivot stop pin 64 may extend from eachcradle support 47 to prevent each mandrel cradle 51 from pivoting beyondthe position shown in FIG. 6.

The jack screws and ball nuts 63 a can be extended from the respectivejack screw housings 63 of the respective pair of jack screw housingservo motors (I/O to raise each yoke assembly 56, via the linear railcarriage 57, through the corresponding module slot 16 (FIG. 1) in thetable module 2. At a certain point during the lift, one leg of eachmandrel cradle 51 indexes one of a left hand mandrel 88 and a right handmandrel 88 a, as shown in FIG. 5, during fabrication of a stringer 93(FIG. 38), which will be hereinafter described. Continuing through thelift, a certain point is reached upon which the slider links 48 and theyoke assembly 56 reach their slide limit and force the mandrel cradles51 to rotate. The halfway point of this rotation of the mandrel cradles51 is shown in FIG. 5. Once the mandrel cradles 51 have rotated oppositeone another and are locked into position by the ball detents 52,actuation of the jack screws and ball nuts 63 a is reversed and thelinear rail carriage 57 travels downwardly on the carriage tracks 58. Asthe linear rail carriage 57 continues its downward travel on thecarriage tracks 58, the mandrel cradles 51 bump against the fixedcabinet 55 to release the ball detents 52, such that gravity returns themandrel cradles 51 to the upright position.

As shown in FIGS. 1, 2, 7 and 8, the table module 2 of the structureassembly table 1 further includes multiple positioning assemblies 70which facilitate selective positioning of the composite assembly andcomposite assembly components along the transverse axis of the tablemodule 2 during fabrication of a stringer 93. In a typical embodiment,the structure assembly table 1 includes five positioning assemblies 70.As shown in FIG. 1, each positioning assembly 70 is typically providedbetween adjacent module units 8.

As shown in FIGS. 7 and 8, each positioning assembly 70 typicallyincludes a pair of generally parallel, spaced-apart vertical carriagesupports 71. A vertical carriage 72 is slidably mounted on each verticalcarriage support 71. An I/O capable vertical servo motor 73 is providedon each vertical carriage support 71 and operably engages eachcorresponding vertical carriage 72 to facilitate vertical travel of eachvertical carriage 72 on the corresponding vertical carriage support 71.Fasteners 74 attach each vertical carriage support 71 of the positioningassembly 70 to a corresponding unit connector 11 which connects theadjacent module units 8 of the table module 2 to each other.

An elongated transverse carriage support 76 extends between the verticalcarriages 72. The transverse carriage support 76 may be attached to thevertical carriages 72 via a pair of gusseted angle attach brackets 75,for example. A transverse carriage 77 is slidably mounted on thetransverse carriage support 76. A riser block 78 is provided on thetransverse carriage 77. A cover 79, such as a delrin cover, for example,is provided on the riser block 78. An I/O capable transverse servo motor80 operably engages the transverse carriage 77 to facilitate selectivetravel of the transverse carriage 77 along the transverse carriagesupport 76. As shown in FIG. 7, a photoelectric sensor 81 is provided onthe cover 79, which is adapted to detect the edge of a compositestructure subassembly on the riser block 78 at five different locationsof the composite structure subassembly during fabrication of thecomposite structure, as will be hereinafter described. In anillustrative embodiment of the structure assembly table 1, thephotoelectric sensors 81 are spaced at forty (40) inch centers per tablemodule 2. By operation of the vertical servo motors 73, the verticalcarriages 72 travel vertically on the respective vertical carriagesupports 71 and raise and lower the transverse carriage support 76 andriser block 78 with respect to the top surface of the table module 2. Byoperation of the transverse servo motor 80, the transverse carriage 77and riser block 78 travel in a selected direction along the transversecarriage support 76.

As further shown in FIGS. 1 and 2, a compactor head 84 extends throughthe module slot 16 of each module unit 8. A compactor assembly (notshown) is typically supported by the module unit frame 9 of each moduleunit 8, beneath the top plate 14. The compactor assembly typicallyincludes a pneumatically-actuated cylinder (not shown) which engages thecompactor head 84 to facilitate selective bidirectional travel of thecompactor head 84 along the module slot 16 of the corresponding moduleunit 8. Accordingly, responsive to operation of the compactor assembly,the compactor head 84 is capable of travel between the far rightposition shown in FIG. 23 and the position shown in FIG. 24 for purposeswhich will be hereinafter described.

A computerized controller (not shown) is connected to the actuatingballscrew housing servo motor (I/O) 20 and the actuating ballscrewhousing servo motor (I/O) 36 of each flipper assembly 18; the actuatingjack screw housing servo motor (I/O) 63 (FIG. 2) of each flopperassembly 44; and the servo motors (I/O) 73 and the servo motor (I/O) 80(FIG. 8) of each positioning assembly 70 to facilitate automatedfabrication of a composite structure 87, as will be hereinafterdescribed with respect to FIGS. 9-38.

Referring next to FIGS. 9-38, implementation of the composite structureassembly table 1 in the fabrication of a composite aircraft stringer 93(FIG. 38) will be described. It will be recognized and understood thatthe composite structure assembly table 1 can be configured to fabricatea variety of composite aircraft stringers 93. Furthermore, the compositestructure and assembly table 1 can be readily re-configured toaccommodate stringers of various sizes and configurations, as needed.Multiple table modules 2 can be placed in end-to-end relationship withrespect to each other to form a composite structure assembly table 1 ofselected length depending on the length of the aircraft stringer 93 tobe fabricated using the composite structure assembly table 1.

In FIG. 9, operation of the composite structure assembly table 1 beginsby controller input of table configuration, depending on the type ofaircraft stringer 93 (FIG. 38) which is to be fabricated, into thecomputerized controller (not shown). The table configuration includessuch parameters as the length of the stringer 93 and the variations inthickness along the length of the stringer 93, for example. In FIG. 10,the flopper assemblies 44 are operated to extend the pairs of mandrelcradles 51 through the respective module slots 16 (FIG. 1) in the tablemodule 2 of the structure assembly table 1. In FIG. 11, a left handmandrel 88 and a right hand mandrel 88 a, each of which receives a pairof respective C-shaped stringer charges 89, is placed on the mandrelcradles 51 of the flopper assemblies 44. The left hand mandrel 88 andright hand mandrel 88 a extend in generally parallel relationship withrespect to the longitudinal axis of the table module 2 and each other.

In FIGS. 12 and 13, the mandrel cradles 51 of the respective flopperassemblies 44 are rotated outwardly to turn the left hand mandrel 88 andright hand mandrel 88 a and respective stringer charges 89 away fromeach other in a horizontal orientation, as shown in FIG. 13. The flopperassemblies 44 are shown with the mandrels 88, 88 a and stringer charges89 in the raised position in FIG. 5. In FIG. 14, the mandrel cradles 51are lowered to rest the mandrels 88, 88 a onto the top plates 14(FIG. 1) or top surface of the table module 2. In FIG. 15, the mandrelcradles 51 are lowered beneath the surface of the table module 2.

In FIG. 16, left hand mandrel 88 and composite charge 89 are sensed forlocation then lifted. A traverse move of the riser blocks 78 positions88 and 89 next to support pins 26 of fixed flipper 19 as shown in FIG.17. In FIG. 18, the riser blocks 78 of the positioning assemblies 70have sensed position relative to the right-hand mandrel 88 a and 89 byoperation of the photoelectric sensors 81. Then, the right-hand mandrel88 a is lifted above the surface of the table module 2. The left-handmandrel 88 remains on the top surface of the table module 2, aspreviously located. In FIG. 19, the positioning assemblies 70 areoperated to move the riser blocks 78, and the right-hand mandrel 88 a,toward and adjacent to the left-hand mandrel 88. In FIG. 20, the riserblocks 78 (FIG. 7) have been lowered beneath the top surface of thetable module 2 to rest the right-hand mandrel 88 a on the table module2. Next, the photoelectric sensors 81 (FIG. 7) on the respective riserblocks 78 sense the location of the edge of the right-hand mandrel 88 a.This location is used by the system controller to calculatestraight-line final placement of the right-hand mandrel 88 a.

In FIG. 21, the riser blocks 78 have located the right-hand mandrel 88 aand lifted the right-hand mandrel 88 a above the top surface of thetable module 2. This step begins final placement of the right-handmandrel 88 a. In FIG. 22, the riser blocks 78 have moved the right-handmandrel 88 a toward and immediately adjacent to the left-handed mandrel88, with the webbing of the stringer charges 89 on the respectivemandrels 88, 88 a typically disposed in contact with each other. In FIG.23, the riser blocks 78 have been lowered beneath the top surface of thetable module 2.

In FIG. 24, the compactor assembly (not shown) has moved the compactorhead 84 from the far right-hand “home” position at the non-operator side5 of the table module 2, as shown in FIG. 23, toward and then againstthe right-hand mandrel 88 a, as shown in FIG. 24. The left-hand mandrel88 engages the support pins 26 on the respective flipper blades 23 (FIG.2) of the flipper assemblies 18. Therefore, the webbing of the C-shapedstringer charges 89 on the respective mandrels 88, 88 a are pressedagainst and joined to each other under pressure for a time. In FIG. 25,the compactor head 84 has returned to the far right-hand “home” positionat the non-operator side 5 of the table module 2.

In FIGS. 26 and 27, the flipper assemblies 18 have begun to raise thefixed position flipper device 19 and the adjustable position flipperdevice 30 above the plane of the top surface of the table module 2. Theflipper blade 23 of the fixed position flipper device 19 rotates themandrels 88, 88 a and connected stringer charges 89 about ninetydegrees. At the end of the lifting or rotating movement, the mandrels88, 88 a and connected stringer charges 89 are positioned between theflipper blade 23 of the fixed position flipper device 19 and the flipperblade 35 of the adjustable position flipper device 30, as shown in FIG.27. In FIG. 28, the mandrels 88, 88 a and stringer charges 89 have beentransferred from the flipper blade 23 of the fixed position flipperdevice 19 to the flipper blade 35 of the adjustable position flipperdevice 30. In FIG. 29, the flipper blade 23 and the flipper blade 35have been lowered beneath the top surface of the table module 2, withthe mandrels 88, 88 a and stringer charges 89 resting on the operatorside top surface of the table module 2. It will be appreciated by thoseskilled in the art that the independent adjustment capability of theadjustable position flipper device 30 of each flipper assembly 18 arecapable of compensating for taper and ply thickness variations along thelength of the mandrel assembly. Referring again to FIG. 2, the linearslide 38 facilitates positioning of each adjustable position flipperdevice 30 with respect to the corresponding paired fixed positionflipper device 19 during repositioning of the mandrel assembly in orderto compensate for these taper and ply thickness variations.

In FIG. 30, a radius filler 91 is applied to the triangular crevicewhich extends between and along the connected stringer charges 89. Abottom cap 90 is applied to the stringer charges 89, over the radiusfiller 91. Application of the radius filler 91 and bottom cap 90 to thestringer charges 89 can be carried out using a manual process, accordingto the knowledge of those skilled in the art.

In FIGS. 31-33, the mandrels 88, 88 a and connected stringer charges 89are raised from the surface of the table module 2 and rotated 90 degreesas they are transferred from the flipper blade 35 of the adjustableposition flipper device 30 to the flipper blade 23 of the fixed positionflipper device 19. The mandrels 88, 88 a and stringer charges 89 areadditionally shown engaged by the flipper assemblies 18 in the raisedposition in FIG. 3. The mandrels 88, 88 a and stringer charges 89 arethen rotated another 90 degrees as the flipper blade 23 of the fixedposition flipper device 19 rests the mandrels 88, 88 a and stringercharges 89 on the top surface of the table module 2, respectively. InFIG. 34, the riser blocks 78 of the positioning assemblies 70 havelocated and raised the mandrels 88, 88 a and stringer charges 89 abovethe surface of the table module 2 and support pin 26. In FIG. 35, theriser blocks 78 have moved the mandrels 88, 88 and stringer charges 89to the operator side 4 of the table module 2.

In FIG. 36, the riser blocks 78 have lowered the mandrels 88, 88 a andstringer charges 89 onto the top surface of the table module 2. In FIG.37, a radius filler 91 is applied to the triangular crevice between thestringer charges 89. A top cap 92 is applied to the stringer charges 89,over the radius filler 91. Application of the radius filler 91 and topcap 92 to the stringer charges 89 can be carried out using a manualprocess, according to the knowledge of those skilled in the art. Asshown in FIG. 38, application of the radius filler 91 and top cap 92 tothe stringer charges 89 completes fabrication of the stringer 93. Thecompleted stringer 93 is then readied for access by an operator fortransport from the structure assembly table 1 to a subsequent processingstation (not shown).

Although this invention has been described with respect to certainexemplary embodiments, it is to be understood that the specificembodiments are for purposes of illustration and not limitation, asother variations will occur to those of ordinary skill in the art.

1. A device for moving a pair of mandrel cradles, comprising: at leastone carriage track; a linear rail carriage carried by said at least onecarriage track; a yoke assembly carried by said linear rail carriage; alinear actuator assembly engaging said linear rail carriage and adaptedto move said linear rail carriage along said at least one carriagetrack; a pair of mandrel cradles each pivotally carried by said yokeassembly, each of said mandrel cradles mounted to independently pivotwith respect to said yoke assembly and with respect to each otherbetween a first and second position; and activation of said linearactuator assembly facilitates movement of said linear rail carriagealong said at least one carriage track and pivoting of said pair ofmandrel cradles between said first and second position.
 2. The device ofclaim 1 wherein said at least one carriage track comprises a pair ofgenerally elongated, parallel carriage tracks.
 3. The device of claim 1wherein each of said pair of mandrel cradles has a generally L-shapedconfiguration.
 4. The device of claim 1 wherein said linear actuatorassembly comprises an actuating mechanism engaging said linear railcarriage.
 5. The device of claim 4 wherein said actuating mechanismcomprises at least one jack screw.
 6. The device of claim 4 furthercomprising at least one gang beam carried by said linear rail carriage.7. The device of claim 1 further comprising a pair of cradle positionblocks pivotally carried by said yoke assembly and wherein said pair ofmandrel cradles is carried by said pair of cradle position blocks,respectively.
 8. The device of claim 7 further comprising a curved slotprovided in each of said pair of cradle position blocks and a ballplunger carried by said yoke assembly and extending through said slot.9. A device for moving a pair of mandrel cradles, comprising: at leastone carriage track; a linear rail carriage carried by said at least onecarriage track; a yoke assembly carried by said linear rail carriage; aflopper frame having a pair of spaced-apart cradle supports carried bysaid yoke assembly; a linear actuator assembly engaging said linear railcarriage and adapted to move said linear rail carriage along said atleast one carriage track; a pair of mandrel cradles pivotally carried bysaid pair of spaced-apart cradle supports, respectively; and a pair ofcradle position blocks pivotally carried by said pair of spaced-apartcradle supports, respectively, and wherein said pair of mandrel cradlesis carried by said pair of cradle position blocks, respectively;activation of said linear actuator assembly facilitates movement of saidlinear rail carriage, along said at least one carriage track andpivoting of said pair of mandrel cradles with respect to said pair ofspaced-apart cradle supports, respectively.
 10. The device of claim 9wherein said at least one carriage track comprises a pair of generallyelongated, parallel carriage tracks.
 11. The device of claim 9 whereineach of said pair of mandrel cradles has a generally L-shapedconfiguration.
 12. The device of claim 9 wherein said linear actuatorassembly comprises an actuating mechanism engaging said linear railcarriage.
 13. The device of claim 12 wherein said actuating mechanismcomprises at least one gang screw.
 14. The device of claim 12 furthercomprising at least one gang beam carried by said linear rail carriage.15. The device of claim 9 further comprising a curved slot provided ineach of said pair of cradle position blocks and a ball plunger carriedby said yoke assembly and extending through said slot.
 16. A device formoving a pair of mandrel cradles, comprising: a cabinet having a trackplate and a pair of spaced-apart side plates extending from said trackplate; at least one carriage track carried by said track plate; a linearrail carriage carried by said at least one carriage track; a yokeassembly carried by said linear rail carriage; a flopper frame having anelongated crosspiece carried by said yoke assembly and a pair ofspaced-apart cradle supports carried by said crosspiece; a pair ofslider links carried by said pair of spaced-apart side plates,respectively, of said cabinet; a pair of ball detents extending fromsaid pair of slider links, respectively; a pair of cradle positionblocks having a pair of curved slots, respectively, receiving said pairof ball detents, respectively; a pair of ball plungers extending fromsaid pair of cradle supports, respectively, of said flopper frame andthrough said pair of curved slots, respectively, of said pair of cradleposition blocks; a pair of mandrel cradles pivotally carried by saidpair of cradle position blocks, respectively; a linear actuator assemblyengaging said linear rail carriage and adapted to move said linear railcarriage along said at least one carriage track; and activation of saidlinear actuator assembly facilitates movement of said linear railcarriage along said at least one carriage track and pivoting of saidpair of mandrel cradles with respect to said pair of spaced-apart cradlesupports, respectively.
 17. The device of claim 16 wherein said at leastone carriage track comprises a pair of generally elongated, parallelcarriage tracks.
 18. The device of claim 16 wherein each of said pair ofmandrel cradles has a generally L-shaped configuration.
 19. The deviceof claim 16 further comprising a pair of elongated gang beams engagingsaid linear rail carriage and wherein said actuating mechanism comprisesa jack screw engaging said linear rail carriage.